This invention relates to a melt-spinning process for production of polyester fibers. More particularly, it relates to continuous transport of a polyester melt from a melt source to a melt-spinning operation. In one preferred embodiment the invention relates to a process involving a continuous polyester polycondensation system coupled with a continuous melt-spinning system.
Pertinent patents include U.S. Pat. No. 3,480,706 to Carpenter et al. on a melt-spinning process involving continuously transferring and pumping a molten thermo-plastic polymer from a condensation reactor to a spinning pack; U.S. Pat. No. 3,758,658 to Riggert on a melt spinning process featuring the steps of supplying a polymer melt at a temperature below the spinning temperature and heating the melt prior to filament formation; and U.S. Pat. No. 3,000,053 to Hart on a melt spinning apparatus wherein the holdup time of the spinning composition in the system is maintained constant. More recently, Geiger in Verfahrenstechnic 9, No. 1 (Mainz) (1975), discloses a method for optimization of transfer lines for high viscosity liquids.
Accordingly, it is well known in this art to continuously transfer and/or pump and/or filter a thermoplastic polymer melt prior to melt-spinning. However, the prior art does not disclose a polyester transfer process that provides low thermal degradation of the polyester during transfer. It is important that in terms of polymer degradation, a transfer process that is eminently suitable for heat-sensitive polyester polymers would not be equally suitable for other polymers such as polyamide polymers. In this regard, the extent of degradation of the polyester polymer during transfer may be estimated from the rate of carboxyl formation.